Auto-coulping PID Control Method for LCL Grid-connected Inverter Current
A current control method based on auto-coupling PID control theory is proposed to address the issues of slow current tracking speed and large overshoot when the power of three-phase grid connected inverters suddenly changes.This method considers the known or unknown internal dynamics of LCL type three-phase grid connected inverter and the disturbances caused by the grid voltage as total disturbances,and then the nonlinear disturbance system can be equivalent to a linear disturbance system.Furthermore,a controlled error system under the inverse excitation of total disturbance is constructed.An auto-coupling PI current controller based on speed factor is designed accordingly.Theoretical analysis shows that the auto-coupling PI closed-loop control system has good robust stability and disturbance resistance robustness.Simulation experiments have shown that this method has dynamic qualities such as fast response speed,high control accuracy and strong anti-interference ability.The response time is about 2 ms,and the proposed method has good practical application prospects in the field of distributed power grid connection.
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